Today's electronic devices rely on conventional silicon technology. With silicon technology, one can fabricate the electronic components (e.g. transistors, diodes, switches, memory, integrated circuits and processors) needed to produce modern computers and consumer electronic products. Silicon-based electronics have been remarkably successful in the market place and have provided a number of conveniences that have greatly simplified everyday life.
The growth of silicon-based electronics over the past few decades has been propelled by the enormous strides that have been made in the miniaturization of devices during manufacturing. Miniaturization trends have faithfully followed Moore's Law for many years over many generations of silicon technology. As device feature sizes decrease, it becomes possible to include ever more devices in a given area of a silicon wafer and to achieve improved performance and speed from computers and electronic products.
Since future improvements in computing power and functionality are currently predicated on further improvements in silicon technology, there has been much recent discussion about the prognosis for continued miniaturization of silicon-based electronic devices. A growing consensus is emerging that believes that the computer industry is rapidly approaching the performance limits of silicon. The feature size in today's manufacturing technologies is 0.18 micron and it is expected that this can be reduced to about 0.10 micron in the future. Further decreases in feature size, however, are deemed problematic because sizes below about 0.10 micron lead to a change in the fundamental behavior of silicon. More specifically, as the dimensions of silicon devices decrease to tens of nanometers and below, silicon enters the quantum regime of behavior and no longer functions according to the classical physics that governs macroscopic objects. In the quantum regime, energy states are quantized rather than continuous and phenomena such as tunneling lead to delocalization of electrons across many devices. Consequences of tunneling include leakage of current as electrons escape from one device to neighboring devices and a loss of independence of devices as the state of one device influences the state of neighboring devices. In addition to fundamental changes in the behavior of silicon, further decreases in the dimensions of silicon devices also pose formidable technological challenges. New innovations in fabrication methods such as photolithography will be needed to achieve smaller feature sizes.
Two other drawbacks of silicon technology have been identified. First, the costs of installing and operating new manufacturing facilities have increased exponentially as feature sizes have decreased. At today's 0.18 micron feature size, for example, the cost of building a new semiconductor fabrication facility exceeds a billion dollars. This cost will only increase as devices become smaller and more susceptible to impurities and process contamination. Second, there is growing recognition that the functionality of silicon-based computers is inherently limited as certain computations remain largely unamenable to solution by modern computers. Examples include factoring, parallel computing, pattern recognition and associative memory. Similarly, many tasks that are readily and intuitively performed by humans and other biological organisms are difficult, cumbersome and oftentimes impossible to implement with conventional computers.
Consideration of the future of computing indicates a need for new computers with new functionality to address ever more sophisticated applications. New computers that are adaptable and flexible and that operate according to reasoning and intelligence are needed. A need exists for computers that are not limited to the rigid, brute force problem solving methodology of conventional computers. Instead, computers are needed that can respond to changing situations with an ability to discriminate information from multiple sources to provide reasoned outputs, even in the face of seemingly conflicting circumstances. The functionality required to achieve intelligent computers and devices extends beyond the current and projected performance capabilities of the silicon technology underlying conventional computers. Consequently, a need exists for a new and revolutionary computing paradigm that encompasses general purpose computers and task-specific computing devices as well as their underlying electronic components and materials.